Gupta, S. P.

Singh, Jai

English

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INDIAN J. CHEM., VOL. 14A, SEPTEMBER 1976Pd(II) Chelate of 2,4-DihydroxyvalerophenoneOximeTABLE 1 - SYNTHESIS AND CHARACTERISTICSOF Sb(III)-SCHIFFBASE COMPLEXESMolar Reflux Mol. formularatio periodhrFound (%) (calc.)Sb NSCHIFFBASEFROMn-PROPYLAMINE1: 1 4t Sb(OPri}.(C1OH1.NO)* 30·62 3·64(30·35) (3-49)1:2 7 Sb(OPri) (CloHuNO)~ 23·96 5·45(24-12) (5'54)1:3 9t Sb(CIOH12NO)~ 19·74 6·64(20'03) (6,91)SCHIFF BASE FROMn-BUTYL AMINE1: 1 3 Sb(OPri)2 (CllH14NO)* 25·36 3·28(26,05) (3'36)1: 2 7 Sb(OPri)(CllHuNO)~ 21·98 5·14(22'85) (5'25)1: 3 8t Sb(CllH14NO)i 18·53 6·49(18,74) (6,46)SCHIFF BASE FROMANILINE1:1 3 Sb (OPri). (C13HIONO)t 27·54 3·16(27'93) (3'21)1:2 4 Sb(OPri}(C13HIONO)~ 20·64 4·62(21'23) (4-88)1:3 8 Sb(C13H'ONO)i 16,62 5·76(17,14) (5,91)*Compounds obtained as yellow liquids.+Compounds obtained as yellow semisolids.tCompounds obtained as yellow solids.o as well as N atoms. A strong band in the region1640-1620 em+ in the Schiff bases due to >C=N-group remains almost unaltered in the resultingderivatives8,9-ll. In the IR spectra of the com-plexes, the appearance of a nEW strong band at600 ± 10 cm-1 may be attributed to vSb-O.The antimony isopropoxide was prepar~d. bythe sodium chloride methods and was distilled(105°/14 mm) before use: Schiff bases'' and thei.rderivatives+ were synthesized as usual. The expcn-mental details of all the reactions are summarizedin Table 1. Antimony was estimated as antimonouspyrogallate", while nitrogen by Kj,~ldahl.'s methodsIsopropanol was estimated by oxiuimetric methodusing IN KzCrzO, in 12'5% H2S04,References1. MEHROTRA,R. C. & BHATNAGAR,D. D., J. Indian chem,Soc., 42 (1965), 327.2. KUMAR, K., MISRA, S. N. & KAPOOR, R. N., Indian J.Chem., 7 (1969), 1249.3. KUMAR, K. & KAPOOR, R. N., Egypt. J. Chem., 15(1972), 613.4. MEHROTRA, R. C., RAI, A. K. & BOHRA, RAKESH, J.Indian chem, Soc., 51 (1974), 304.5. DUBROVINA,O. D., Chern. Abstr., 51 (1957), 6453i.6. MEHROTRA, R. C. & DAYAL, J., Indian J. Chem., 10(1972), 435. . ., . .7. VOGEL,A. 1., A text book of quamtitatiue inorgamc analysts(Longmans, Green, London), 1961, 502.8. BRADLEY, D. C., HALIM, F. M. A. & WARDLAW, W.,J. chem, Soc., (1950), 3450.9. SHARMA,B. D. & BAILER (Jr). J. C., J. Am. chem, Soc.,77 (1955), 5476.10. BIRADAR,N. S. & KULIARNI, V. H., J. inorg, nucl. Chem.,33 (1971), 3781.11. PRASAD, R. N. & TANDON, J. P., Z. Naturf., 28b(1973), 153.710JAI SINGH & S. P. GUPTAChemistry Department, D.N. College, Meerut 250002Received 20 June 1975; accepted 12 March 19762,4-Dihydroxyvaleropbenone oxime forms water in-soluble complex with Pd(II) which is extractable intochloroform to give a yellow solution having 1max at400 nm. It has been found to be a good and selectivereagent for gravlmetrtc estimation of palladium andfor its separation from other ions. The structure ofthe 1:2 (metal: ligand) chelate bas been confirmed byelemental analysts, pH-metric titration, spectrophoto-metric, IR and UV spectral studies. The stabilityconstant of tbe chelate is 6·4 x 10'. Beer's law is obeyedin the concentration range 35-75 ppm of Pd(II). Limitsof interference due to the presence of foreign ions in thespectrophotometric and gravimetric determinations.have been determined.IN continuation of our studiesv+ on the chelatesof 2,4-dihydroxyvalerophenone oxime (DHVOX),this note deals with the gravimentric ar d spectro-photometric determination oi Pd(II) with DHVOX.The composition and structure of the Pd(II) chelatehave also been determined on the basis of analytical,pH-metric titration, IR and UV spectral data.All the measurements were carried out afterequilibrating the solutions at 30° ± 0·2° for 30 min.DHVOX Was prepared as reported earlier". Solutionof Pd(II) Was prepared by dissolving palladiumchloride (BDH, AR) in 0'05N HCl. All the otherchemicals used were of BDH, AR. grade and wereused as such.The method of Vcsburg and Coopers showed thatPd(II) forms only one complex which has Amax at400 om. The complex can be extracted in chloro-form, carbon tetrachloride or ethyl acetate. How-ever, chloroform is found to be a better solvent forextraction. The subsequent studies were carriedout in this medium. In all the experiments 8 mlof chloroform Was used for extraction. Preliminarystudies showed that the absorption is maximumbetween pH 2·0 and 5'0. Subsequent studies werecarried at PH 3'0. Four-fold excess of the ligandWas necessary for maximum colour intensity. Beer'slaw is followed over the concentration range 35-75ppm of Pd(II). From the slope ratio curve themolar extinction coefficient was found to be 7,68 X102 and sensitivity = 0,139 t.t.g Pd/cm2•Composition oj the complex - The compositionof the complex was found to be 1: 2 by mole-ratiomethod", slope-ratio method' and Job's methodof continuous variation, extended to a two phasesystem by Irving and Pierces.The stability constant of the complex was cal-culated by the molar ratio method, using the rela-tion:K =(1-oc)/4C2oc3 and o: =(E",-Es)/E",where Em, Es, IX. and C have their usual meanings.The stability constant was found to be 6,4 X 10'at 400 nm and standard energy of formation (-6.F =RT In K) was found to 10·38 kcaljrnole at 30°C.NOTESThe composition of the complex was furtherconfirmed by potentiometric, conductometric andanalytical studies. Metal-ligand ratio was alsodetermined by the method of Fenger et al.9 andfound to be 1: 2.The IR spectrum of DHVOX showed strongbands at 3500 em+ ('JOH) , 3380 cmt ('JOR chelated),3280 em+ ('JOH of =N-OH), 2980 cm-l and 2800crrr+ ('JCH of methylene groups), 1650 cnr? ('JC=N),830 cm-l (1,2,4-trisubstituted benzene) and 990cm-l ('IN-O). Examination of the IR spectrumof the chelate shows that the phenolic hydrogen isreplaced by the metal because the band at 3280cm-l due to hydroxyl group of the oximino moietyappears more or less at the same position in both,the ligand and the complex, and. 3380 crrr+ peakof the chelated OH disappears 111 the complex.In the chelate the band at 1650 cm-l disappearsand a stronger band appears at 1590 ~:n::-l, whichcan very likely be assigned to 'JC=N shifting down-field, due to complexation. The 'IN -0 bandappearing at 990 em? in the ligand ~h~fts downfieldto 960 cm-l in the chelate. The posvtion of 'IN-Oband has been confirmed by various workers10,ll.The band at 3500 cm-l in the spectrum of chelateis ~ssigned to the hydroxyl group. at .positio~1-4which does not take part In coordination. Nc,:,",bands appearing at 580 and 515 crrr" may be attri-buted to metal-nitrogen and metal-oxygen stretch-ing modes respectively-t-P. On the basis of abovedata structure (1) may be assigned to the complex.Three spin allowed d-d transitions are expectedfor square-planar Pd(II) complex. Only two bandsat 28570 and 42850 crrr? have been observed 111the electronic spectra of Pd(CllH14NOah Followingthe assignment of Mason and Gray]4 the band at28570 crrr ' can be treated as a combination of allthe three spin allowed transitions.(lAIg-+lA2g;~lEIg;-+lBlg) _. 5The other band at 42850 cm-l is due to the +ransition-lA g--+ClEu• The values of ligand field para-meters ~l' ~2 and ~3 have been found to be 32070,1500 and 500 crrr? respectively. _ _Procedure for the spectrophotometric determinationof Pd(II)- A suitable aliquot of palladium solutioncontaining 35-50 [lg of Pd(II) Was taken ar d suffi-cient excess of DHVOX was added. The pH waskept at 3·0 by adding 2 ml of suitable buff:-r ~r:dethanol concentration was 25% in the final dilution.The precipitate was extracted into 8 ml of chloro-form, The organic layer was separated, waterdroplets removed by centrifugation and the absor-bance measured at 400 nm against reagent blankprepared under similar conditions, From theabsorbance value, concentration of metal can beevaluated with help of the previously preparedcalibration curve.It was observed that for a 50 ppm concentrationof palladium, 2000 ppm concentration of CHaCOO-C4Hga:""N/OHI ~0.. ,Pd/2HO 0ITABLE 1- DETERMINATION OF PALLADIUMPalladiumtaken(mg)(PH of thePalladiumcomplexobtained(rng)24-6026-2036-8078-60104-40131-00156-00182-20209-00+0-40±O-OO+0-13±O-OO-0-09+0-08-0-40-0-50-0-005solution 3-0)Palladiumfound(mg)Error(%)5-025'387-5116-0021-3226-7431-8637-2042-665-005-387-5016-0021-3426-7232-0037-3842-68and SO!-; 1000 ppm concentrations of Ba(II), Sr(II),Ca(II), Be (II) , Cd(Il), Fe(II), Mg(II), K(I), NH4(I),Na(I), ci. Be, NO; and ClO'4; 500 ppm concen-tration of Cr(III), Pb(II), Ag(I), citrate and tartrate;100 ppm concentrations of Co(II), Ni(II) and Mn(II)could be tolerated. But Fe(III), Cu(II) and V(V)interfere seriously.Gravimetric estimation. of Pd(II)- An aliquotcontaining ......,10rog of Pd Was diluted to 100-125ml ar.d PH adjusted between Z·Oand 8·0 with hydro-chloric acid ar:d ammonia buffer. The contentswere heated to 70-80° and treated with 0'5% ethanolicsolution of DHVOX added dropwise with constantstirrirg (about twice the theoretical amount). Theyellow precpitate obtained was digested on a water-bath for 30 min and filtered through a G-4 sinteredglass crucible, It was washed with hot waterseveral times and finally with ZO% ethanol anddried at 110-20° to a constant weight. It hasbeen found that the precipitation of palladium isquantitative in the PH range Z-0-8·0 although pre-cipitation starts at pH 1·0_ The conversion factor(metal/metal complex) is 0·20413_ Some represen-tative results are given in Table l.Determination of palladi~£m in the presence ofother ions - The procedure was the same as in theabsence of foreign ions. The interference in somecases was removed by working at low pH to preventthe precipitation of corresponding hydroxides.Interference due to Sb(III), Bi (III), Fe (IIl) andAs(III) was removed by adding tartaric acid (? g).By suitable adjustment of pH, about 5 to 10 timesexcess of a large number of cations could be tole-rated, e.g. Fe (II) , Fe(IlI), Bi(III) , Sb(III) andAs(III) at pH 2·5; and Ni(II), Co(II), Zn(II), Cd(II),Mo(VI), Mn(II), Mg(II) , \V(VI) and U(VI) at pH3·5 could be tolerated, About 10-100-fold excessof several anions, e.g. POi-, ci-. Be, I-, F-, B40~-,S01- and tartrate could be tolerated at PH 3-0__From the solution containing both palladiumand nickel, palladium was first precipitated asindicated above at PH 3·0 and from the filtratenickel was precipitated by addition of more reagentand adjustment of PH in the range 7'0-8-0 as report-ed:! earlier. The results are reproducible with anerror ±0'5% for amounts of Pd(U) tanging from5·0 to 43·0 mg. The reagent is readily preparedand is less expensive than the various other reagentsreported in the literature.711INDIAN J. CHEM., VOL. 14A, SEPTEMBER 1976The authors are thankful to Dr Nitya Nand,Director, CDRI, Lucknow, for IR and UV spectraand microanalysis.References1. SINGH, J., GUPTA, S. P. & MALIK, o. P., Indian]. Chem.,13 (1975), 1217.2. SINGH, J., GUPTA, S. P. & MALIK, O. P., J. Indian chem,Soc., 52 (1975), 656.3. SINGH, J. & GUPTA, S. P., J. Acta Ciencia Indica, 1(1975), 107.4. SINGH, J. & GUPTA, S. P., Curro Sci., 44 (1975), 612.5. VOSBURG, W. C. & COOPER, G. R, J. Am. chem, Soc.,63 (1941), 437.6. YOE, J. H. & JONES, A. L., Ind. Engng Chern: analyt,Edn, 16 (1944), 111.7. HARVEY, A. E. & MANNING, D. L., J. Am. chem, Soc.,72 (1950), 4488.8. IRVING, H. & PIERCE, T. B., J. chem, Soc., (1959),2565.9. FENGER, J., SIEKIESKA. K. E. & JENSEN, B. S., J. inorg.nucl. Chem., 33 (1971), 4366.10. BLINKS, R & HADZI, D., J. chem, Soc., (1958),4536.11. PALM, A. & WERBIN, H., Can. J. Chem., 31 (1953), 1004.12. BIRADAR. N. S. & MAHALE. V. B., J. less-common Metals,31 (1973). 159.13. GHOSH. N. N. & GUPTA. M. D., J. Indian chem. Soc., 51(1974). 206.14. MASON. W. R & GRAY, H. B., J. Am. chem, Soc .• 90(1968). 5721.15. MASON, W. R & GRAY, H. B., Tnorg, Chern., 7 (1968).55.Malate Complex of AI(III)NIRADA KUMARI MOHANTY & R. K. PATNAIKDepartment of Chemistry, Regional Engineering CollegeRourkela 769008Received 9 October 1975; accepted 16 January 1976Malate complex of aluminium has been studiedpH-metrically in the pH range 2·8-8·0. AlH reactswith malic acid in the pH range 2·8-3·4 to form aneutral complex (C) with simultaneous liberation of 3protons. At higher pH, the neutral complex (C) under-goes step-wise dissociation to form anionic complexes(Ci) and (C~-). The equilibrium constants of the threereactions,AI3++HzML<=C+3H+C <=Ci+H+or <=C~-+H+are found to be 4·12x 10-6, 1·91x 10-' and 2·58x 10-8respectively.PAVLINOV A and Vysotskaya- have studied thecomplex formation between A!3+ and malicacid by potentiometric and conductometric titra-tions. This note reports the pH-metric determi-nation of stability constants of malate complexesof Al (III) in the PH range 2·8-8,0.A~uminium perchlorate was prepared by dis-solving a known amount of aluminium hvdroxide(prepared from a known amount of aluminiumsulphate) in a known weight of standardized 70%perchloric acid. The solution was diluted to onelitre and then aluminium estimated as A120a (ref. 2)and as Al(C9H60N)3 (ref. 3). The excess perchloricacid present in the solution was neutralized bystandard sodium hydroxide solution after the addi-tion of known amount of malic acid.The following solutions (total volume 200 ml)were titrated against 0·1111 NaOH:(i) 6·063 X 10-4111malic acid +0·01111 NaCI04712(ii) 4·997 X 10-4M AI(CIO,h+6'063 X lO-'M malicacid+O'OlM NaClO,[iir) 2·425 X 1O-3M malic acid+O'OlM NaCIO,(iv) 4·997 X 10-4111 Al(CIO,,)3+2'425X 1O-3M malicacid+O'OlM NaCI04(v) 6·25 X 10-4M sodium malatt+O·OlM NaCl04(vi) 4·997 X 1O-4M AllCl04)s+6·25X 1O-4M sodiummalate+O'OlM NaClO"(vii) 2·5 X 10-3M sodium malate-l-Il-Ill Zf NaCI04(viii) 4·997 X 10-4111Al(CI04la+2'5 X 1O-3M sodiummalate+O·OlM NaCI04.As observed in the case of cadmium citrate+,manganese tartrate" and other systemsv", theamount of acid liberated during the complex for-mation between AP+ and malic acid remains thesame even though the metal-ligand ratio is increasedfrom 1: 1·25 to 1: 5 indicating the formation of a1: 1 complex. The reaction between malic acidand aluminium perchlorate [titrations (i)-(iv)] maybe represented by Eq. 1.AI3++H2ML ~ C+nH+K = [C] X [H+J"[AP+JfHzML]By proceeding in the same manner as describedin the case of cadmium citrate+ system, it can beshown that, .~[NaOH] -ajM,[ML] jb[C] = n-awhere 6.[NaOH]=[NaOH]B-[NaOH]A~[ML]=[ML]B-[MLJAkl 2klk2 kl klk2a = [H1 + [H+J2' b = 1+ [H+] + [H+J2-kl and k2• the dissociation constants of malic acid"are 5·5 X 10-4 and 2·1 X 10-5 respectively.When the formation of the complex is complete,it can be shown that,~[NaOH1-ajM,[ML] _ j[AI(CI04laJ - n-a b ... (4)Using Eq. 4, the n values at different pH canbe calculated frem the titration curves (i) and (ii)and the values arc found to be higher than 3 and4 at ~/)H ~ 3·6 and 6·2 respectively. Below pH3·6, a neutral complex C is formed and assumingthe n value to be 3, below PH 3·6, K values werecalculated and found to be 4·68 X 10-6, 4·22 X 10-6,4'24xl0-6, 3'94xl0-6 and 3'52xlO-6 at PH 2·8,2'9, 3'0, 3·1 and 3·3 respectively. The mean valueof K is 4·12 X 10-6.In the pH range 3·6-6·2, the n values are greaterthan 3, but less than 4. This indicates the disso-ciation of neutral complex (C) according to Eq. 5.C~Cl+H+ ... (5)and[C~][H+]Kl=-~ ...(6)It can be shown as in the case of cadmium citratecomplex+ that,K1= (n-3)[H+](4-n)The values of KI were calculated using Eq. 7and found to be 1·56x 10-5, 2·62x 10-5, 2·33 X 10-5,... (1). .. (2)... (3)•.. (7)

Pd(II) Chelate of 2,4-Dihydroxyvalerophenone

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Pd(II) Chelate of 2,4-Dihydroxyvalerophenone

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